The present invention relates to a laser cutting machine, and in particular to a laser cutting machine suitable for cutting thin metal plates or other thin plates.
The focusing head of the laser cutting machine is supported by a jointed support structure in such a way that it is free to move. The support structure is driven so that it moves the head through a predetermined path. It is well-known that in a more sophisticated machine that path could be three-dimensional. In this method any arbitrary shape can be cut in a plane or conical metal plate.
The laser used in the machine has reached a very high degree of perfection, and is capable of cutting both thin metal plates and very thick plates of other materials, but, nevertheless, satisfactory results are not always obtained. In practice, at times the cuts obtained are not as clean or as accurate as desired.
The defect is generally caused not by the focusing lens but by small, randomly distributed undulations on the surface of the thin plate. These undulations cannot be taken into account in the head motion program and are an important cause of defects. It is well known that in order to obtain perfect cuts, the bundles of laser light rays must be focused exactly at an accurately determined and rigorously constant distance from the surface of the work piece. Clearly, every time an undulation is reached along the cutting path the distance changes, as a result of which only part of the laser light energy is transmitted to the work piece.